Make sure your phone is on stock 8.1.1 (OTA updates, no other changes. If you've made any changes you must flash back to 8.0 using my tutorial and then take OTA updates to 8.1.1).
Hard reset your phone twice (I boot while holding Vol Down to reach the exclamation point symbol, and then hard reset with the combo Vol Up>Vol Down>Power>Vol Down).
Upon initial setup, connect to WiFi, connect your Microsoft account (do NOT restore a backup), and wait for all apps to finish updating.
Install Preview for Developers and move it to your SD card.
Register your phone as a development device using the 8.1 SDK on your computer.
Sideload CustomWPSystem.
Use CustomWPSystem to patch Preview for Developers with CustomPFD_0300.xap (must be 0.3, not 0.5 or 0.6).
Soft reset (hold power and Vol Down until it reboots).
Open Preview for Developers (which is really CustomPFD).
Navigate to HKLM>System>Platform>DeviceTargettingInfo.
Change phoneManufacturer to NOKIA and phoneManufacturerModelName to RM-927 (this is the Lumia Icon, which has the same chipset/architecture as the Ativ SE, and it has Verizon provisioning).
Install Windows Insider, and use it as you would normally.
You'll get the update to 10536, and WiFi will remain functional. DO NO DO A HARD RESET FROM 10 OR YOU WILL NEED TO REFLASH 8.0 AND START AGAIN!